How directional microphones affect speech recognition, listening effort and localisation for listeners with moderate-to-severe hearing loss

Abstract

Objective: The purpose of this study was to evaluate the effects of directional microphone use on laboratory measures of sentence recognition, listening effort and localisation. An additional purpose of this study was to evaluate the effects of asymmetric directional microphone use on the same laboratory measures. Design: Three hearing aid conditions were evaluated: (1) bilateral omnidirectional microphones, (2) bilateral directional microphones and (3) asymmetric microphones (directional microphone for only one hearing aid). Sentence recognition performance was evaluated using a connected speech test. Listening effort was evaluated using a dual-task paradigm with a response time-based secondary task requiring word categorisation. Localisation was examined using a complex task requiring localisation and recall of speech originating from one of four loudspeakers in the horizontal plane (−60°, −45°, +45°, +60°). Study sample: Eighteen adults (M = 61.8 years) with symmetrical, moderate-to-severe hearing loss participated. Results: Performance on each task was analysed separately using a repeated measures analysis of variance. Results revealed directional benefits for sentence recognition and listening effort, but microphone setting did not affect localisation. Performance was equivalent with symmetric and asymmetric directional configurations. Conclusions: Bilateral and asymmetric directional microphone configurations equally improved sentence recognition and listening effort; neither affected localisation or recall.

Key Words:

• Hearing aids
• hearing loss
• noise
• rehabilitation
• cognition
• speech perception
• listening effort
• localisation

Acknowledgements

The authors wish to thank Daniel Krass and Kristen D’Onofrio for their assistance in data collection. Portions of this project were presented at the Scientific and Technical Conference of the American Auditory Society (March 2014, Scottsdale AZ). This project was funded by GN Resound and by the Dan and Margaret Maddox Charitable Fund.

Declaration of interest

The authors have no conflicts of interest to report.